500L fps>>pressure correlation

[Snyd]

So I'm working up a load for this 525 LFN LBT boolit from a mould princeout has kindly loaned me for a time. With my alloy they weigh 540gr lubed with check. I think the mould was designed to drop 525 with ww/lino 50/50. At any rate...

LBT on left CP 525 on right.



I can't find any data for LilGun so I used quickload to get an idea of where to start. I plugged in the measurements of the boolit, etc. and it came up with 22gr of LIlGun being 90% load density, psi 23690, fps 950. Sounded like a good place to start. I don't trust software but in playing with the numbers it seemed low enough to allow a safe margin. Well I fired one round over the chrony and it was 1115fps! I stopped there. 

Any idea what pressure this load may have been? 35,000ish plus?

FWIW QL shows 24gr at 31600psi, 1043fps which I figured sounds good if it's accurate. I'd say QL is way off with this combo.

I'm thinking I'll drop to 20gr and work up in .5 increments and see what I get. I'm looking for an accurate load between 1000-1100 without being on the ragged edge of high end pressure.

[jdoc]

If the bullets are the same length and diameter. The difference in weight should be within 25 to 35 grains. Unless you are using zinc as the casting material. Something is out of spec. Are you sure you have a correct weight for your bullet. Just for kicks weigh the CP 525 bullet on the same balance used to weigh the bullet from Tim's mold. Who is the mold manufacturer/mold model number? I would not do anymore testing till a culprit is found. A damaged or destroyed octagon barreled Bowen 500L is not a cheap custom to replace.

I have to do some research of my notes before I comment much more.

[Paden]

Must be a typo; that bullet can't possibly weigh only 340(?)!

[Snyd]

Yup Typo... duh.. fat fingered that one. It weighs 540gr NOT 340. I fixed it in the original post.

[Paden]

Oct 16, 2015 20:06:08 GMT -5 Snyd said:

Yup Typo... duh.. fat fingered that one. It weighs 540gr NOT 340.

Mo Betta!

Gonna watch the rest of this one from the bench. You're playing out of my league.

[Fowler]

I wondered if he cast it from aluminum to have it only be 340!

[Seasons44]

www.hodgdonreloading.com/data/pistol

I don't run lil gun for the 500, but if you have 4227 the load is 28 grains for a 525.

[jefats]

I shoot 525 LFN/GC by Bryan Reece which are right on the button weightwise and measure 17BHN. 15.5 HS-6 and standard WLP give me 994 f/s. Another load I like is 11.0 Universal at 880 f/s.

These type loads are easy on the gun and shooter.

[frankenfab]

How do the outside of the cases and the primers look with that load?

If you can't trust the velocity estimate of the software, you can't trust the pressure estimate, either. It could be wrong in the other direction.

Interesting, thanks for bringing it up.

[Snyd]

Oct 18, 2015 21:01:56 GMT -5 frankenfab said:

How do the outside of the cases and the primers look with that load?

If you can't trust the velocity estimate of the software, you can't trust the pressure estimate, either. It could be wrong in the other direction.

Interesting, thanks for bringing it up.

Well I only shot the one round. Case dropped out of the cylinder with just a tap of the ER. Primer is not flattened. I'm not sure what I should be looking for on the outside of the case.

[frankenfab]

"I'm not sure what I should be looking for on the outside of the case.

Sooty case indicates lower pressure.

If you can see every tool mark from the chamber on the outside of the case, she's runnin' perty hot.